1. Field of the Invention
The present embodiments relate to methods for improving semiconductor process uniformity, and more particularly, methods, systems, and computer programs for reducing chamber instability while processing a semiconductor substrate.
2. Description of the Related Art
Plasma has long been employed to process substrates (e.g., wafers or flat panels) to form electronic products (e.g., integrated circuits or flat panel displays). In plasma processing, a process gas may be injected into a chamber and energized to form a plasma to either deposit a layer on the substrate or to sputter or etch the substrate. In some processes, particularly those involving deep etching of the silicon layer, there exist various etch techniques that alternate etching and deposition sub-steps in order to perform the etch more anisotropically (e.g., forming sidewalls of the trenches or holes more vertically).
However, sometimes chamber conditions do not stay unchanged over time. Undesired phenomena, such as chamber drift (e.g., a situation in which the chamber conditions change from substrate to substrate due to, for example, polymer deposition), may render the values of the parameters in the chamber, that are found to be optimally for the first substrate, non-optimal for subsequent substrates. Accordingly, the etch result for the substrates may not be uniform, thereby impacting the repeatability of the etch process and affecting the quality of the end product.
It is in this context that embodiments arise.